Suppose I have a dataclass: @dataclass(frozen=True) class Foo: id: str name: str I want this to be immutable (hence the frozen=True), such that foo.id = bar and foo.name = baz fail. But, I want to be able to strip the id, like so: foo = Foo(id=10, name="spam") foo.strip_id() foo -> Foo(id=None, name="spam") I have tried a few things, overriding setattr, but nothing worked. Is there an elegant solution to this? (I know I could write a method that returns a new frozen instance that is identical except that that id has been stripped, but that seems a bit hacky, and it would require me to do foo = foo.strip_id(), since foo.strip_id() would not actually change foo) Edit: Although some commenters seem to disagree, I think there is a legitimate distinction between 'fully mutable, do what you want with it', and 'immutable, except in this particular, tightly controlled way' Continue reading...
